Purpose <p>Patients with terminal cancer often have swallowing dysfunction (dysphagia), which is associated with quality of life. Dysphagia has been reported to be associated with cancer treatment, physical decline, or poor eating posture. However, its relationship with activities of daily living (ADLs) and eating posture has rarely been studied. This study examined these associations in patients with terminal cancer.</p> Methods <p>This cross-sectional observational study included patients admitted to a palliative care unit between November 2018 and April 2024 who underwent rehabilitation. Data included age, sex, swallowing function (Functional Oral Intake Scale [FOIS]), ADLs (Functional Independence Measure [FIM]), eating posture (upright sitting, chair sitting, full gatch-up, high-angle, low-angle), and Palliative Prognostic Index (PPI). Patients were categorized into tube-dependent (FOIS 1–3) and oral intake (FOIS 4–7) groups. Group comparisons used the Mann-Whitney <i>U</i> test. Multivariate logistic regression examined associations between swallowing function, ADLs, eating posture, adjusting for age, sex, PPI, and sleepiness.</p> Results <p>Among 201 patients (mean age 82.0 ± 10.8&#xa0;years), 26.4% were tube-dependent. Swallowing function was significantly associated with mFIM (odds ratio [OR] 1.03, 95% confidence interval [CI] 1.01–1.05, <i>P</i> = 0.002), cFIM (OR 1.07, 95% CI 1.02–1.12, <i>P</i> = 0.002), total FIM (OR 1.03, 95% CI 1.01–1.05, <i>P</i> &lt; 0.001), and upright sitting (OR 2.92, 95% CI 1.12–7.62, <i>P</i> = 0.029).</p> Conclusion <p>Swallowing function in patients with terminal cancer was associated with ADLs and eating posture. The cross-sectional design limits causal inference, and prospective studies are needed.</p>